Liquid Pentablock Co-Polymer Formulations for Sustained Delivery of Therapeutics

ABSTRACT

Provided herein are amphiphilic polymers compositions for making aqueous formulations. In one aspect, a solution composition for delivery and release of active ingredients comprises a block co-polymer having formula: PEG-PCL-PLA-PCL-PEG or PGA-PCL-PEG-PCL-PGA or PLA-PCL-PEG-PCL-PLA or PCL-PLA-PEG-PLA-PCL or PCL-PGA-PEG-PGA-PCL. The block co-polymers are biodegradable, stable and compatible with hydrophilic, hydrophobic, and combinations thereof, biologic or chemical active agents. In some embodiments, the block co-polymers enable sustained and/or continuous release of various active agents. In certain embodiments, the block co-polymers can be used to make an artificial tear preparation, a lubricant for joints or wound cover or adhesive.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. application Ser.No. 15/582,685, filed Apr. 29, 2017, which claims priority to and thebenefit of U.S. Provisional Application Nos. 62/330,010 filed Apr. 29,2016 and 62/456,921 filed Feb. 9, 2017, the entire disclosures of eachof which are incorporated herein by reference.

FIELD

The compositions and methods disclosed herein relate to biodegradable,biocompatible and amphiphilic pentablock co-polymers, specificallyaqueous formulations that are useful for sustained delivery ofhydrophobic and hydrophilic therapeutics.

BACKGROUND

Various block polymer compositions are known in the art. For example,triblock polymers such as the PCL-PEG-PCL and PLA-PEG-PLA triblockpolymers comprised of polyethylene glycol (PEG) and poly(ε-caprolactone)(PCL), and polylactide (PLA) are disclosed by Cha et al., U.S. Pat. No.5,702,717 and Lui et al. (Thermoreversible gel-sol behavior ofbiodegradable PCL-PEG-PCL triblock copolymer in aqueous solutions, J.Biomed. Mater. Res. B. Appl. Biomater., January, 2008, 84 (1) 165-75).The individual polymers forming the block polymer are all well-known,FDA-approved, biodegradable, and biocompatible materials.

In addition, the pentablock co-polymer PLA-PCL-PEG-PCL-PLA has beenstudied by Deng et al. (Synthesis and Characterization of Block Polymersof ε-Caprolactone and DL-Lactide Initiated by Ethylene Glycol or Poly(ethylene glycol), J. Polymer Sci., 1997, Vol 35 No. 4 703-708); Kim etal. (The Synthesis and Biodegradable behavior of PLA-PCL-PEG-PCL-PLAMulti Block Copolymer, Polymer Preprints, 2000, Vol. 49 No. 71557-1558). These insoluble polymers were proposed as tissue scaffoldsby Huang (Polymeres Bioresorbables Dérivés de Poly(ε-caprolactone) enIngénierie Tissulaire, Centre de Recherche surles BiopolyméresArtificiels, UMR CNRS 5473 Faculté de Pharmacie, Université MontpellierI en collaboration avec Division de Bioingénierie, Université Nationalede Singapour).

Pentablock co-polymer compositions described to form nanoparticles witha bioactive agent are disclosed by U.S. Pat. No. 8,551,531, PCTPublication No. WO2014/186669, and Patel et al. (Novel ThermosensitivePentablock Copolymers for Sustained Delivery of Proteins in theTreatment of Posterior Segments Diseases, (2014) pp. 1185-1200), all ofwhich are incorporated herein by reference. However, currently availablecompositions are typically only compatible with either hydrophobic orhydrophilic active agents, not both. Furthermore, hydrophobic activeagents and combinations of hydrophilic and hydrophobic active agents canbe difficult to formulate, in particular in the form of clear, aqueoussolutions. Therefore, a need exists for improved aqueous formulationsthat can deliver various active agents to patients in need thereof.

SUMMARY

The present disclosure, in one aspect, is directed to compositions ofamphiphilic pentablock co-polymers (PTSsol) useful for the aqueousformulations of hydrophilic and/or hydrophobic active ingredients, suchas biologics and small molecule drugs useful in the treatment ordiagnosis of a variety of disorders or diseases. In some embodiments,the compositions disclosed herein can be used for sustained release ofsuch active ingredients in liquid formulation over a prolonged period oftime. The amphiphilic pentablock co-polymers when dispersed in aqueousmedium, can include small size particles (e.g., <1 μm in diameter) andmay be, without wishing to be bound by theory, micellar in nature, andare suitable for sustained drug release of small molecule drugs andbiologicals through various routes of administration. The polymers canbe thermosensitive in nature. In some embodiments, the compositions canbe such that they are liquid at about 4° C. and may only become slightlymore viscous at body temperature (about 37° C.) but do not visibly gelwhich is highly desirable for the liquid formulations. For example, ifused for topical application on ocular surface, the compositionsdisclosed herein can extend the release time of active ingredients(e.g., hydrophobic drugs that are especially difficult to solubilize)to, e.g., 1-48 hours and longer, compared to 5 minutes or less withoutthe pentablock co-polymer compositions herein. When applied topically tothe eye, the small size particles loaded with a drug can easilypenetrate ocular surface and deliver drug in sufficient concentration tothe back of the eye to be of therapeutic value. If injected intravitrealin the eye, intra articular in the knee or other joints, or intravenousfor systemic circulation, the compositions disclosed herein can extendthe release time of active ingredients to, e.g., at least 1 day and upto 6 months and longer. Other sustained release applications includetopical application on dermal surface (e.g., for psoriasis or burnwounds) and subcutaneous injection.

In particular, one aspect of the present disclosure provides acomposition for delivery of an active ingredient, comprising a co-blockpolymer having the formula of PEG-PCL-PLA-PCL-PEG in the form of anaqueous solution, wherein PEG is polyethylene glycol and has an averagemolecular weight of about 100 to about 10,000 Da and a molecular weightpercentage of at least 25%, wherein preferably PEG has an averagemolecular weight of about 500 to about 5,000 Da; wherein PCL ispoly(ε-caprolactone) and has an average molecular weight of about 100 toabout 3000 Da, preferably about 200 to about 2000 Da, and morepreferably about 300 to about 1500 Da; wherein PLA is polylactic acidand has average molecular weight of about 100 to about 5,000 Da,preferably about 150 to about 3000 Da, and more preferably about 200 toabout 1500 Da; and wherein the polymer preferably has a total molecularweight of about 1,500 to about 20,000 Da, more preferably about 2,000 toabout 15,000 Da, even more preferably about 2,500 to about 10,000 Da.

In another aspect, a composition is provided for delivery of an activeingredient, comprising a co-block polymer having the formula ofPGA-PCL-PEG-PCL-PGA in the form of an aqueous solution, wherein PEG ispolyethylene glycol and has an average molecular weight of about 100 toabout 10,000 Da and a molecular weight percentage of at least 25%,wherein preferably PEG has an average molecular weight of about 500 toabout 5,000 Da; wherein PCL is poly(ε-caprolactone) and has an averagemolecular weight of about 100 to about 3000 Da, preferably about 200 toabout 2000 Da, and more preferably about 300 to about 1500 Da; whereinPGA is polyglycolic acid and has average molecular weight of about 100to about 5,000 Da, preferably about 150 to about 3000 Da, and morepreferably about 200 to about 1500 Da; and wherein the polymerpreferably has a total molecular weight of about 1,500 to about 20,000Da, more preferably about 2,000 to about 15,000 Da, even more preferablyabout 2,500 to about 10,000 Da.

In some embodiments, the PTSsol polymers disclosed herein may increasein viscosity but do not visibly gel at, e.g., 37° C. (body temperature)or higher temperatures and are sometimes referred to as non-gellingpolymers. The non-gelling polymer can be present in small or largeamounts, e.g., at about 0.01 to about 50 wt % of liquid formulation,preferably about 1 to about 35 wt %, more preferably about 2 to about 25wt %. The composition can further comprise an aqueous medium and anactive ingredient that is hydrophobic or hydrophilic admixed therein.The aqueous medium is water in one example. The active ingredient can bepresent at about 0.01 wt % to about 50 wt %, preferably about 0.1 toabout 30 wt %, more preferably about 0.2 to about 10 wt %. The activeingredient can be a biologic or chemical agent. The active ingredientcan be hydrophobic or hydrophilic, or a mixture of hydrophobic andhydrophilic ingredients.

In certain embodiments, the composition can further comprise of gellingpolymers wherein adding one or more of non-gelling polymers preventgelation of the gelling polymers. The gelling polymers can be present insmall or large amounts, e.g., at about 0.01 to about 25 wt % of theliquid formulation, preferably about 1 to about 15 wt %, more preferablyabout 2 to about 10 wt %. The non-gelling can be present at 0.01 to 49.9wt % of liquid formulation. The composition can further comprise anactive ingredient that is hydrophobic or hydrophilic and is dissolved ordispersed in the polymers.

In a further aspect, an artificial tear comprising an aqueous solutionof any of the compositions disclosed herein is provided. The aqueoussolution may, in some embodiments, include one or more of amphiphilicpolymer excipients, tonicity agents, buffers, sugars selected fromtrehalose, mannose, D-galactose, and lactose, preservatives, co-solventsor antioxidants. The aqueous solution can have a pH ranging from about5.0 to about 8.0, preferably about 6.6 to about 7.4, and more preferablyabout 7.0.

Another aspect relates to a method for preparing an aqueous formulationof a hydrophobic active ingredient, comprising: dissolving or dispersingthe hydrophobic active ingredient in a gelling polymer, and admixingwith any composition containing a non-gelling polymer as disclosedherein, wherein the gelling polymer can be present at about 0.01 toabout 25 wt % of the liquid formulation, preferably about 1 to about 15wt %, more preferably about 2 to about 10 wt %.

Also, provided herein is a method of delivering an active ingredient toa mammal in need thereof, comprising: providing any compositiondisclosed herein admixed with an active ingredient, wherein the polymeris present at between about 0.01 wt % and about 50 wt % of the liquidformulation, preferably about 1 to about 35 wt %, more preferably about2 to about 25 wt %; wherein the composition is in the form of a clear ornear clear dispersion; and administering the composition to a mammal. Insome embodiments, said administering is by a topical, oral or parenteralroute.

In certain embodiments, the polymer disclosed herein bio-degrades orclears at a rate substantially similar to release rate of an activeingredient, allowing for repeat applications without interferingbiologically or physically with a prior application. The polymer maybiodegrade successively into substituent blocks, which are notsubstantially physiologically harmful, and wherein the polymer and thesubstituent blocks from biodegradation are tolerated in vivo such thatlong-term or repeat applications are feasible.

In some embodiments, the particle size (in diameter) of the polymer ofthe present disclosure in aqueous medium as determined by DLS (Dynamiclight scattering) can range from about 5 nm to about 1 μm, preferablyabout 7-200 nm, more preferably about 10-100 nm, and most preferablyless than about 30 nm. This is a particle size that normally escapes thetypical response of the body's immune system by being able to avoidphagocytosis and has enhanced permeability through biological membranes.Thus, PTSsol dispersed in aqueous medium, are comprised of small sizeparticles of amphiphilic in nature with high drug loading capacity ofboth hydrophobic and hydrophilic drugs that are suitable for sustaineddrug release of small drug molecules and biologicals through variousroutes of administration. In addition, the polymers described arebiocompatible and biodegradable.

BRIEF DESCRIPTION OF THE DRAWINGS

The present technology will be further explained with reference to theattached drawings. The drawings shown are not necessarily to scale, withemphasis instead generally being placed upon illustrating the principlesof the present disclosure.

FIG. 1, left panel illustrates clear aqueous formulation for 1% and 2.5%brinzolamide and 1% cyclosporine A combined with an exemplary PTSsol atDay 0 and Day 28. The formulations remained visibly clear, when storedrefrigerated for 28 days without drugs precipitating out. Right panelillustrates an exemplary 0.07% and 0.1% difluprednate PTSsol after 8days of storage under refrigerated conditions. The formulation remainedvisibly clear for 8 days without drug precipitating out.

FIG. 2 shows stability by HPLC analysis (96.9%), of 2.5% Brinzolamideprepared in PTS 1-0GH and stored for 8 weeks at 4° C.

FIG. 3 shows stability of 1% Brinzolamide in PTS 1-0GH stored ure at 4°C. and 20° C. for 8 weeks (analyzed by HPLC analysis to be 93-100%).

FIG. 4 illustrates a visibly clear formulation of exemplary PTSsolartificial tears containing 1-20% of PTS 121GH non-gelling polymer. Theformulation stored at room temperature remained visibly clear for 21days after preparation.

FIGS. 5A-5B show exemplary PTSsol are liquid at both 4° C. and at bodytemperature (about 37° C.).

FIG. 6 shows NMR of PTS 121GH.

FIG. 7 shows GPC analysis of PTS 121GH. Polydispersity (Mw/Mn): 1.053(±3.986%).

FIG. 8 shows Dynamic Light Scattering (DLS) of PTS 1-0GH dispersion inwater (1mg/mL).

FIG. 9. shows sustained release of NIR-IgG for >21 h after topicalocular application of NIR-IgG in PTSsol in mice.

FIG. 10 shows PD effect for IOP reduction in normotensive dogs after oneapplication a day of BRZ 2.5% (prepared in PTSsol), compared againstAzopt® 1%, three times a day.

While the above-identified drawings set forth certain exemplaryembodiments, other embodiments are also contemplated, as noted in thediscussion. This disclosure presents illustrative embodiments by way ofrepresentation and not limitation. Numerous other modifications andembodiments can be devised by those skilled in the art which fall withinthe scope and spirit of the principles of the presently disclosedembodiments.

DETAILED DESCRIPTION

The present disclosure is directed to pentablock co-polymers useful forbiodegradable and biocompatible aqueous drug delivery systems. Theamphiphilic pentablock co-polymers described herein may be used fordelivery, in particular the sustained delivery of biologics, or smallmolecules, irrespective of their hydrophobic or hydrophilic nature,contained therein. In some embodiments, the compositions disclosedherein can be used for sustained release of various active ingredientsover a prolonged period of time. For example, if used for topicalapplication on ocular surface, the compositions disclosed herein canextend the release time of active ingredients to, e.g., 1-48 and longerhours, compared to about 5 minutes or less without the pentablockco-polymer compositions herein. Topical ocular application of drugs inPTSsol has the potential to deliver drugs to the back of the eye insufficient concentration to be of therapeutic value. If injectedintravitreal in the eye or intra articular in the knee or other joints,the compositions disclosed herein can extend the release time of activeingredients to, e.g., at least 1 day and up to 6 months and longer.Other sustained release applications include topical application ondermal surface (e.g., for psoriasis or burn wounds) and subcutaneousinjection. The compositions in some embodiments can also be provided forintra venous injection for systemic circulation for, e.g., chemotherapy(e.g., paclitaxel, doxorubicin, etc.) or organ transplant rejection(e.g., cyclosporin). The small size particles can easily avoidmononuclear phagocytic system and therefore drug can be delivered to thetargeted site. The small size particles are formed just by dispersingthe polymer in aqueous medium. It does not require intervention of anorganic solvent and sonication etc.

Conventionally, liquid drops (e.g., solutions or suspensions) whenapplied to ocular surface last for only about 5 minutes or less. Theliquid amphiphilic pentablock co-polymer formulation described herein,when applied topically to eye surprisingly becomes bioadhesive orviscous (possibly without blurring), significantly increases contacttime (e.g., 1-48 hours and longer) with ocular surface and hence allowshigher drug penetration into the eye. Another advantage, without wishingto be bound by theory, is that the liquid pentablock co-polymerformulation described herein appears to form micelles (typical particlesize about 5-200 nm, about 10-100 nm or <1 μm in diameter that arepresent in the aqueous polymer dispersion) which will also help improvedrug penetration into the eye. Typically eye drops (e.g., commercialAzopt®, a milky suspension of 1% brinzolamide which is used in glaucomato reduce IOP in the eye) need to be applied 3 times a day. As shown inthe Examples and as exemplary embodiments, the amphiphilic pentablockco-polymer formulation disclosed herein can be used to make clearsolution of Brinzolamide (e.g., 2.5% as tested in dogs) and need to beapplied for only once a day or less for better results compared toAzopt®. This is a significant improvement over the prior technology. Insome embodiments, due to small particle size of amphiphilic nature ofthe compositions of the present disclosure, which would easily dispersein aqueous formulation without the help of organic solvents orsonication etc., evade elimination by immune system, high loadingcapacity of hydrophobic and/or hydrophilic drug, biocompatible andbiodegradable, mucoadhesive and muco-penetratable nature, this resultsin a very unique sustained drug release formulation including but notlimited to for topical, dermal, intravitreal or parenteral applications.Because the polymers disperse in aqueous medium as small size particles(<1 μM), penetration through ocular surface may deliver drugs to theback of the eye in significant concentration to be of therapeutic value.

The present disclosure is also directed to methods for fabricating theamphiphilic pentablock co-polymers disclosed herein, as well ascompositions comprising the biodegradable and biocompatible pentablockco-polymers with hydrophilic and/or hydrophobic drugs, such as biologicsor small molecule drugs, in particular in the form of aqueous solutions.The present disclosure is well adapted for the administration of thehydrophilic and hydrophobic drugs, or combinations thereof, particularlyhydrophobic drugs that are generally difficult to solubilize.

Specifically, some hydrophobic drugs are known to be difficult toformulate in aqueous formulations and therefore, are formulatedtypically as emulsions or suspensions. Using the present disclosure,however, hydrophobic drugs can be formulated at significantly high drugconcentrations as clear liquid in certain hydrophilic or in combinationwith non-gelling polymers disclosed herein. As a result, clinicallyrelevant formulations can be generated for various applications, such asocular, topical, oral, and/or parenteral delivery. These formulationsare referred to as “PTSsol” in some embodiments. As demonstrated herein,in one example, 10% of 121GH polymer can dissolve cyclosporine (CsA) at1% and Brinzolamide (BRZ) at 2.5% and result in very clear liquids. BRZsolutions stored at room temperature or refrigerated at 4° C. remainedclear and stable for 8 weeks (or longer) of testing. Higherconcentrations for CsA or BRZ are feasible. Similarly, PTSsol forcelecoxib (0.5%) was prepared in 121GH.

All polymers are amphiphilic in nature. However, some hydrophobic drugsare very hydrophobic and do not directly dissolve in relatively morehydrophilic polymers (typical for PTSsol). In certain embodiments, thesedrugs (e.g., difluprednate) can first be dispersed in a very smallamount of relatively more hydrophobic gelling polymer such as PTS 113GHor PTS 122GH and then can subsequently be mixed with relatively morehydrophilic PTS121GH to maintain the formulations as liquid at roomtemperature and at body temperature. Using this strategy PTSsolformulations for difuprednate was generated at 0.1% concentration.Higher concentrations are possible.

In various embodiments, the present technology can be used to prepare aformulation having a combination of both hydrophobic and hydrophilicdrugs where desired. For example, this can be achieved by addinghydrophilic drug to PTSsol that has already been generated with thehydrophobic drug.

In some embodiments, PTSsol can be in the form of clear but polymericdispersion of a mixture of molecular weight polymers (e.g.,1500-20,000), the polymers may stay at the surface of the administrationto which they are applied for some length of time. Since the pentablockco-polymers appear to be bio-adhesive and are biocompatible andbiodegradable, such a property can be very useful for applications suchas preparing artificial tears for relieving eye discomfort caused by dryeye. In one example, PTS 121GH vehicle PTSsols with no drug added tohave been prepared in PBS, pH 7.4 at 5-20% polymer concentration. Theseformulations remained clear for at least 21 days stored at roomtemperature as well as at 4° C. Specific drugs tested include 2.5% BRZas small hydrophobic molecule in 25% 1-0 GH, as well as NIR-IgG as anexample for biologics in 25% 121GH and 1-0GH.

PTSsol can be used in various therapeutic formulations such as eye dropsfor topical applications and sprays on the skin (e.g., for wound healingfrom burn or psoriasis and more indications). Since some PTSsol areclear solutions, they can also be used to, e.g., generate injectableformulations including but not limited to for systematic circulation ofdrugs that are not aqueous soluble otherwise. Because the polymersdisperse in aqueous medium as small size particles (<1 μM), penetrationthrough ocular surface may deliver drugs to the back of the eye insignificant concentration to be of therapeutic value.

Definitions

For convenience, certain terms employed in the specification, examples,and appended claims are collected here. Unless defined otherwise, alltechnical and scientific terms used herein have the same meaning ascommonly understood by one of ordinary skill in the art to which thisdisclosure belongs.

For convenience, certain terms employed in the specification, examples,and appended claims are collected here. Unless defined otherwise, alltechnical and scientific terms used herein have the same meaning ascommonly understood by one of ordinary skill in the art to which thisdisclosure belongs.

The articles “a” and “an” are used herein to refer to one or to morethan one (i.e., at least one) of the grammatical object of the article.By way of example, “an element” means one element or more than oneelement.

As used herein, the term “about” means within 20%, more preferablywithin 10% and most preferably within 5%. The term “substantially” meansmore than 50%, preferably more than 80%, and most preferably more than90% or 95%.

As used herein, “a plurality of” means more than 1, e.g., 2, 3, 4, 5, 6,7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, or more, e.g., 25,30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, or more, or anyinteger therebetween.

As used herein, “administering” and similar terms mean delivering thecomposition to an individual being treated. Preferably, the compositionscomprising the pentablock co-polymers of the present disclosure areadministered by, e.g., parenteral, subcutaneous, intramuscular,transdermal, transmucosal, intra-articular, intrathecal, intraocular,intraperitoneal, intravenous, oral or topical routes.

As used herein, “biocompatible” refers to materials or the intermediatesor end products of materials formed by solubilization, hydrolysis, or bythe action of biologically formed entities which can be enzymes or otherproducts of the organism and which cause no adverse effect on the body.

As used herein, “biodegradable” means that the pentablock co-polymer canbreak down or degrade within the body to non-toxic components after allbioactive agent or diagnostic agent has been released.

As used herein, “drug” or “active ingredient” shall refer to anybiologic and/or chemical compound or substance adapted or used for atherapeutic purpose.

As used herein, an “effective amount” means the amount of bioactiveagent or diagnostic agent that is sufficient to provide the desiredlocal or systemic effect at a reasonable risk/benefit ratio as wouldattend any medical treatment or diagnostic test. This will varydepending on the patient, the disease, the treatment being effected, andthe nature of the agent.

As used herein, “gel” or “gelling polymer” when used in reference to thepentablock co-polymers and/or drug combination at a temperature at orabove the LCST (see below), shall be inclusive of such combinations aregenerally semi-solid in nature, such as those disclosed in U.S. Pat. No.8,551,531, PCT Publication No. WO2014/186669 and U.S. ProvisionalApplication No. 62/330,020 entitled “SUSTAINED RELEASE FORMULATION ANDUSE THEREOF” filed Apr. 29, 2016 under Attorney Docket No.129865-010500/PRO, all of which are incorporated herein by reference intheir entirety. The term “gel” when used as a verb, refers to theprocess of forming a gel.

As used herein, “LCST” or “lower critical solution temperature,” refersto the temperature at which the pentablock co-polymer undergoes reversethermal gelation, i.e., the temperature below which the polymer issoluble in water and above which the pentablock polymer undergoes phaseseparation to form a semi-solid containing the drug and the pentablockpolymer. The terms “LCST,” “gelation temperature,” and “reverse thermalgelation temperature,” or the like shall be used interchangeably inreferring to the LCST.

As used herein, “non-gelling polymer” refers to a polymer which is thesame as gelling polymer at room temperature but having a LCST that ismuch higher than body temperature.

As used herein, “hydrophilic” refers to the ability to dissolve inwater. When used in the context of the hydrophilic drugs or diagnosticagents in the present disclosure, the term embraces a drug that ispreferably sparingly soluble, more preferably soluble, still morepreferably freely soluble, and still most preferably very soluble,according to USP-NF definitions.

As used herein, “parenteral” shall mean any route of administrationother than the alimentary canal and shall specifically includeintramuscular, intraperitoneal, intra-abdominal, intra-articular,intra-ocular, subcutaneous, and intravenous.

As used herein, “pharmaceutically acceptable” shall refer to that whichis useful in preparing a pharmaceutical composition that is generallysafe, non-toxic, and neither biologically nor otherwise undesirable andincludes that which is acceptable for veterinary use as well as humanpharmaceutical use. Examples of “pharmaceutically acceptable liquidcarriers” include water and organic solvents. Preferred pharmaceuticallyacceptable aqueous liquids include PBS, saline, and dextrose solutionsetc.

As used herein, “peptide”, “polypeptide”, “oligopeptide,” and “protein”shall be used interchangeably when referring to peptide or protein drugsand shall not be limited as to any particular molecular weight, peptidesequence or length, field of bioactivity, diagnostic use, or therapeuticuse unless specifically stated.

As used herein, “solution,” “aqueous solution,” and the like, when usedin reference to a combination of drug and pentablock co-polymercontained in such solution, shall mean a liquid-based solution havingsuch drug/polymer combination dissolved or substantially uniformlysuspended therein at a functional concentration and maintained at atemperature below the LCST of the block polymer.

As used herein, “thermosensitive” refers to a polymer which exists as agenerally clear solution or dispersion near ambient temperature in waterbut when the temperature is raised to the LCST (which is preferablyabout body temperature for gelling polymers), interact to form a gel.

The term “treatment” or “treating” means administration of a drug forpurposes including: (i) preventing the disease or condition, that is,causing the clinical symptoms of the disease or condition not todevelop; (ii) inhibiting the disease or condition, that is, arrestingthe development of clinical symptoms; and/or (iii) relieving the diseaseor condition, that is, causing the regression of clinical symptoms.

Below, the exemplary embodiments are shown and specific language will beused herein to describe the same. It should nevertheless be understoodthat no limitation of the scope of the disclosure is thereby intended.Alterations and further modifications of the inventive featuresillustrated herein, and additional applications of the principles of thepresent disclosure as illustrated herein, for one skilled in therelevant art, in connection with this disclosure, should be consideredwithin the scope of the present disclosure.

Biodegradable Thermosensitive Pentablock Co-Polymers

The present disclosure is directed to pentablock co-polymers comprisedof (A) PLA, (B) PCL, (C) PEG, and/or (D) PGA. Generally, the co-blockpolymer will be an amphiphilic pentablock co-polymer, i.e., a CBABC,denoted as a “PEG terminal” arrangement or DBCBD type co-block polymer,denoted as a “PEG central” arrangement.

For preparation of the pentablock co-polymer used for the aqueoussolutions of the present disclosure (PTSsol), in some embodiments, thepentablock co-polymer preferably has a PEG-PCL-PLA-PCL-PEG, “PEGterminal” configuration. In some embodiments, the pentablock co-polymerpreferably has a PGA-PCL-PEG-PCL-PGA, PLA-PCL-PEG-PCL-PLA,PCL-PLA-PEG-PLA-PCL and/or PCL-PGA-PEG-PGA-PCL, “PEG central”configuration.

PEG Terminal Composition

For preparation of the pentablock polymer of the present disclosure, thepentablock co-polymer can have a “PEG Terminal” block configuration,comprising CBABC.

The hydrophobic A block segment is preferably derived from a L-lactide.The A block segment preferably comprises PLA having an average molecularweight of 100 to about 5,000 Da, preferably about 150 to about 3000 Da,and more preferably about 200 to about 1500 Da (for example, an averagemolecular weight of about 100 Da, 150 Da, 200 Da, 250 Da, 300 Da, 350Da, 400 Da, 450 Da, 500 Da, 550 Da, 600 Da, 650 Da, 700 Da, 750 Da, 800Da, 850 Da, 900 Da, 950 Da, 1000 Da, 1050 Da, 1100 Da, 1150 Da, 1200 Da,1250 Da, 1300 Da, 1350 Da, 1400 Da, 1450 Da, 1500 Da, 1550 Da, 1600 Da,1650 Da, 1700 Da, 1750 Da, 1800 Da, 1850 Da, 1900 Da, 1950 Da, 2000 Da,2100 Da, 2200 Da, 2300 Da, 2400 Da, 2500 Da, 2600 Da, 2700 Da, 2800 Da,2900 Da, 3000 Da, 3100 Da, 3200 Da, 3300 Da, 3400 Da, 3500 Da, 3600 Da,3700 Da, 3800 Da, 3900 Da, 4000 Da, 4100 Da, 4200 Da, 4300 Da, 4400 Da,4500 Da, 4600 Da, 4700 Da, 4800 Da, 4900 Da, 5000 Da, or some rangetherebetween). An average molecular weight in the range of about200-1200 Da is most preferred. It will be appreciated that in thepreferred embodiment, a linker separates the hydrophobic A block, butthat the average molecular weight referenced for this block refers tothe combined molecular weights of the PLA blocks on both sides of thelinker.

The hydrophobic B block segment is preferably derived from a cycliclactone, and is most preferably derived from ε-caprolactone. Thus, inone aspect, the B block segment comprises PCL having an averagemolecular weight of about 100 to about 3000 Da, preferably about 200 toabout 2000 Da, and more preferably about 300 to about 1500 Da. Forexample, the B block segment is preferably PCL having an averagemolecular weight of about 100 Da, 200 Da, 300 Da, 400 Da, 500 Da, 600Da, 700 Da, 800 Da, 900 Da, 1000 Da, 1100 Da, 1200 Da, 1300 Da, 1400 Da,1500 Da, 1600 Da, 1700 Da, 1800 Da, 1900 Da, 2000 Da, 2100 Da, 2200 Da,2300 Da, 2400 Da, 2500 Da, 2600 Da, 2700 Da, 2800 Da, 2900 Da, 3000 Da,or some range therebetween, and most preferably has an average molecularweight in the range of about 300-900 Da.

The hydrophilic C block segment is preferably PEG having an averagemolecular weight of about 100 to about 10,000 Da and a molecular weightpercentage of at least 25%, wherein preferably PEG has an averagemolecular weight of about 500 to about 5,000 Da.

Thus, in one aspect, a pentablock co-polymers used to make the “PEGterminal” thermosensitive aqueous polymer in accordance with the presentdisclosure may be defined according to the following formula:

PEG_(C)-PCL_(B)-PLA_(A)-PCL_(B)-PEG_(C)

wherein PEG is polyethylene glycol and has an average molecular weightof about 100 to about 10,000 Da and a molecular weight percentage of atleast 25%, wherein preferably PEG has an average molecular weight ofabout 500 to about 5,000 Da; wherein PCL is poly(ε-caprolactone) and hasan average molecular weight of about 100 to about 3000 Da, preferablyabout 200 to about 2000 Da, and more preferably about 300 to about 1500Da; wherein PLA is polylactic acid and has average molecular weight ofabout 100 to about 5,000 Da, preferably about 150 to about 3000 Da, andmore preferably about 200 to about 1500 Da; and wherein the polymerpreferably has a total molecular weight of about 1500 to about 20,000Da, more preferably about 2000 to about 15,000 Da, even more preferablyabout 2500 to about 10,000 Da.

In some embodiments, different forms of PEG can be used, depending onthe initiator used for the polymerization process. For example, the PEGcan be methyl ether PEG (m-PEG). Different molecular weight (MW)combinations of m-PEG as a starting point can also be used. For example,the m-PEG can be a combination of two or more m-PEG having different MWranging from 100-10000 Da, e.g., MW_(X)+MW_(Y) such as MW 400+MW 550 ata 1:1 ratio or any other ratio. The polymers can also be combined aftersynthesis with m-PEG MW_(X) and m-PEG MW_(Y) separately.

A linker, such as diisocyanate, for example 1,4-diisocyanatebutate,1,4-diisocyante phenylene, or hexamethylene diisocyanate can be includedin the PEG terminal polymer.

By varying the molecular weights of the various A, B, and C blocks, thepentablock co-polymers synthesized as disclosed herein have varioushydrophobic and hydrophilic blocks, which affect the molecularinteractions with active agents, the release rate and duration ofrelease of active agents, and the molecular characteristics of thepolymer, such as the formation of an aqueous solution or the ability toachieve a gel composition. Further, the hydrophilic C block and thehydrophobic A and B blocks are synthesized and utilized because of theirunique interactions with hydrophobic and hydrophilic active agents.Generally, for the preparation of aqueous compositions, the hydrophilicC block (PEG block) should be more than 25% by weight, the B block (PCLblock) should be about or less than 50% by weight, and the A block (PLAblock) should be about or less than 40% by weight.

The molecular weight of the water-soluble C block, relative to that ofthe hydrophobic A and B blocks, is regulated sufficiently high to retaindesirable water-solubility and aqueous properties. In addition, for thepreparation of aqueous solutions, the proportionate weight ratios ofhydrophilic C block to the more hydrophobic A and B blocks must also besufficient to enable the block polymer to be highly hydrophilic.

As shown in the following examples, the amphiphilic pentablockco-polymer compounds of the present disclosure are ideally suited toform composition, which may include an effective amount of activeagents, such as biologics or small molecules. In general, the pentablockco-polymer can be designed to have a selected rate of drug release.However, the drug and/or diagnostic agent typically comprises about 0.01to 50 wt % of the composition, more preferably about 0.1 to 30% wt ofthe composition, with about 0.2 to 10 wt being most preferred.

PEG Central Composition

In some embodiments, the pentablock polymer preferably has aPGA-PCL-PEG-PCL-PGA or PLA-PCL-PEG-PCL-PLA or PCL-PLA-PEG-PLA-PCL orPCL-PGA-PEG-PGA-PCL configuration, denoted “PEG central.”

For preparation of the pentablock polymer of the present disclosure, thepentablock polymer can have a “PEG Central” block configuration,comprising DBCBD.

The hydrophobic D block segment is preferably derived from a glycolide.The D block segment preferably comprises PGA or PLA having an averagemolecular weight of about 100 to about 5,000 Da, preferably about 150 toabout 3000 Da, and more preferably about 200 to about 1500 Da (forexample, the D block segment may have an average molecular weight ofabout 100 Da, 150 Da, 200 Da, 250 Da, 300 Da, 350 Da, 400 Da, 450 Da,500 Da, 600 Da, 700 Da, 800 Da, 900 Da, 1000 Da, 1100 Da, 1200 Da, 1300Da, 1400 Da., 1500 Da, 1600 Da, 1700 Da, 1800 Da, 1900 Da, 2000 Da, 2100Da, 2200 Da, 2300 Da, 2400 Da, 2500 Da, 2600 Da, 2700 Da, 2800 Da, 2900Da, 3000 Da, or some range therebetween). While the PGA segment isconsidered hydrophobic, it can be sufficiently hydrophilic to interactwith hydrophilic drugs in some embodiments. The D block can also be PCLhaving an average molecular weight of about 100 to about 3000 Da,preferably about 200 to about 2000 Da, and more preferably about 300 toabout 1500 Da.

The hydrophobic B block segment is preferably derived from a cycliclactone, and is most preferably derived from ε-caprolactone. Thus, the Bblock segment comprises PCL having an average molecular weight of about100 to about 3000 Da, preferably about 200 to about 2000 Da, and morepreferably about 300 to about 1500 Da. The B block can also be PGA orPLA having an average molecular weight of about 100 to about 5,000 Da,preferably about 150 to about 3000 Da, and more preferably about 200 toabout 1500 Da.

The hydrophilic C block segment is preferably PEG having an averagemolecular weight of about 100 to about 10,000 Da and a molecular weightpercentage of at least 25%, wherein preferably PEG has an averagemolecular weight of about 500 to about 5,000 Da.

Thus, in one aspect, a pentablock polymers used to make an aqueousrelease polymer in accordance with the present disclosure may be definedaccording to the following formula:

PGA_(D)-PCL_(B)-PEG_(C)-PCL_(B)-PGA_(D) orPLA_(D)-PCL_(B)-PEG_(C)-PCL_(B)-PLA_(D)

or PCL_(D)-PLA_(B)-PEG_(C)-PLA_(B)-PCL_(D) orPCL_(D)-PGA_(B)-PEG_(C)-PGA_(B)-PCL_(D)

wherein PEG is polyethylene glycol and has an average molecular weightof about 100 to about 10,000 Da and a molecular weight percentage of atleast 25%, wherein preferably PEG has an average molecular weight ofabout 500 to about 5,000 Da; wherein PCL is poly(ε-caprolactone) and hasan average molecular weight of about 100 to about 3000 Da, preferablyabout 200 to about 2000 Da, and more preferably about 300 to about 1500Da; wherein PLA is polylactic acid having an average molecular weight ofabout 100 to about 5,000 Da, preferably about 150 to about 3000 Da, andmore preferably about 200 to about 1500 Da; wherein PGA is polyglycolicacid , having an average molecular weight of about 100 to about 5,000Da, preferably about 150 to about 3000 Da, and more preferably about 200to about 1500 Da; and wherein the polymer preferably has a totalmolecular weight of about 1500 to about 20,000 Da, more preferably about2000 to about 15,000 Da, even more preferably about 2500 to about 10,000Da.

By varying the molecular weights of the various B, C, and D blocks, theamphiphilic pentablock co-polymers synthesized as disclosed herein havevarious hydrophobic and hydrophilic blocks, which affect the molecularinteractions with active agents, the release rate and duration ofrelease of active agents, and the molecular characteristics of thepolymer, such as the formation of an aqueous solution or the ability toachieve a gel composition. Further, the hydrophilic C block and thehydrophobic B and D blocks are synthesized and utilized because of theirunique interactions with hydrophobic active agents. Generally, for thepreparation of aqueous compositions, the hydrophilic C block (PEG block)should be greater than 25% by weight, the B block (PCL block) should beless than 50% by weight, and the D block (PGA or PLA block) should beless than 40% by weight.

The molecular weight of the water-soluble C block, relative to that ofthe hydrophobic B and D blocks, is regulated sufficiently high to retaindesirable water-solubility and aqueous properties. In addition, for thepreparation of aqueous solutions, the proportionate weight ratios ofhydrophilic C block to the more hydrophobic B and D blocks must also besufficient to enable the block polymer to be highly hydrophilic.

As shown in the following examples, the pentablock polymer compounds ofthe present disclosure are ideally suited to form composition, which mayinclude an effective amount of active agents, such as biologics or smallmolecules. In general, the pentablock polymer can be designed to have aselected rate of drug release. However, the drug and/or diagnostic agenttypically comprises about 0.01 to 50 wt % of the composition, morepreferably about 0.1 to 30% wt of the composition, with about 0.2 to 10wt being most preferred.

Pentablock Polymer Properties

The mixture of the amphiphilic pentablock co-polymer used fornon-gelling polymers and thermosensitive gelling polymers and thebioactive agent or diagnostic agent may be prepared as an aqueousdispersion of amphiphilic pentablock co-polymers. In general, this maybe performed by forming a dispersion of the amphiphilic pentablockco-polymers and the bioactive agent or diagnostic agent at a suitabletemperature.

The amphiphilic pentablock co-polymers and bioactive agent or diagnosticagent system will cause minimal toxicity and mechanical irritation tothe surrounding tissue due to the biocompatibility of the materials andwill be completely biodegradable within a specific predetermined timeinterval. The hydrophilic properties of the polymeric matrix can becontrolled by proper formulation of the hydrophilic blocks or mixinggelling and non-gelling co-polymers in desirable proportions.

Pentablock Co-Polymer Applications

The biodegradable thermosensitive aqueous solutions comprising theamphiphilic pentablock co-polymers of the present disclosure provide forthe aqueous delivery of hydrophilic and/or hydrophobic agents, such as abiologics or small molecule drugs. In general, the amphiphilicpentablock co-polymer can be designed to specifically not to instantlygel at body temperature (37° C.) (e.g., within minutes or hours (e.g.,about 4 hours or less)) due to their hydrophilic nature. The pentablockco-polymer may gel in some cases in about 4 hours or longer and/or maybecome more viscous than at 4° C. Further, non-gelling pentablockco-polymers are useful in the preparation of aqueous compositions withhydrophobic active agents that do not easily formulate as aqueouscompositions otherwise.

The biodegradable, thermosensitive amphiphilic pentablock co-polymers ofthe current disclosure can be formulated as pharmaceutical compositions,to be administered to a mammalian host, such as a human patient in avariety of forms, such as an aqueous composition. Suitable forms ofpolymer administration can include topical (ocular, dermal), injectionor administration methods to regions such as: oral, intradermal,intravenous, subcutaneous, intramuscular, intravitreal, intraocular,intraarticular, intracardiac, intralesional, intraperitoneal,intracerebroventricular, intrathecal, intraosseous infusion,intracerebral, intrauterine, intravaginal, extraamniotic,intracavernous, and/or intravesica. The polymers of the presentdisclosure can be used as vitreous body substitutes, for example, foruse in cataract surgery, retinal detachment surgery, and the like, aswell as for ear treatments and oral treatments (e.g., dry mouthtreatment).

The polymers can be administered by in liquid form, as dispersions. Thepolymers can be prepared in water, buffer solution, or optionally mixedwith nontoxic surfactants, glycerol, sugars and other commonly usedexcipients. Under ordinary conditions of storage and use, thesepreparations contain a preservative to prevent the growth ofmicroorganisms.

The amphiphilic pentablock co-polymers of the present disclosure areused to form stable, biodegradable, aqueous solutions. Active agents aregenerally used in the amphiphilic pentablock co-polymers, which areuseful in a variety of therapeutic applications or diagnosticapplications.

Therapeutic applications that can benefit from the use of amphiphilicpentablock polymers as a delivery vehicle can include, but not belimited to, the treatment of various conditions where therapeutics inthe form of an aqueous formulation may be desired. For example, thepolymer composition of the present disclosure can be utilized to delivertherapeutics for the treatment of: age related disorders (e.g., bonedecalcification, menopause, joint degradation), cardiac disorders (e.g.,atrial fibrillation), cancer treatment (i.e. chemotherapy, targetedcancer cell treatments), dermatological preparations and/or disorders(e.g., acne, dermal rashes or infections), immunosuppressants (e.g.,tissue transplants, immune disorders), metabolic conditions (e.g.,diabetes, obesity), muscular-skeletal conditions (e.g.,anabolic/catabolic tissue stimulation, pain management, regeneration oftissue), oral treatments (e.g., dry mouth treatments, delivery ofanalgesics, antibiotics, or other agents), pain management (e.g., acute,chronic, or intermediate duration pain symptoms), psychiatric disorders(e.g., schizophrenia, bi-polar disorder, major depressive disorder),ophthalmic disorders (e.g., glaucoma, macular degeneration) andarthritis.

Exemplary therapeutics that can benefit from the use of amphiphilicpentablock co-polymers as the polymer composition of the presentdisclosure can include various hydrophobic drugs, hydrophilic drugs, orcombinations of hydrophobic and hydrophilic drugs. For example, thepolymer composition can be utilized to deliver therapeutic such as,biologics and small molecule drugs, including but not limited to:angiogenesis inhibitors (e.g., pazopanib), antibiotics (e.g.,penicillins, cephalosporins, carbapenems, macrolides, aminoglycosides,quinolones (e.g., fluoroquinolones), sulfonamides, tetracyclines),anti-inflammatories (e.g., nonsteroid antiinflamatory drugs (NSAIDS)(e.g., celecoxib), cyclooxygenase (COX) inhibitors (e.g., naproxen,difluprednate), Beta-blockers (e.g., propranolol), calcium channelblockers (e.g., verapamil), chemotherapeutics (e.g., tyrosine-kinaseinhibitors (e.g., gleevec), cytotoxic antibiotics- (e.g., bleomycin),topoisomerase inhibitors (i.e., topotecan), hormones (e.g., estrogen,testosterone, human growth hormone, prolactin), immunosuppressants(e.g., cyclosporine), metabolic regulatory modalities (e.g., insulin),pain medications (e.g., narcotics, NSAIDS, opioids), psychiatric drugs(e.g., antidepressants, antipsychotics, mood stabilizers), ophthalmicmedications (e.g., carbonic anhydrase inhibitors-brinzolamide,prostaglandin analogues), steroids (e.g., progestogens-progesterone,corticosteroids, mineralocorticoids-aldosterone,glucocorticoids-cortisol, androgens-testosterone, estrogens-estrogen),stem cells (e.g., burn wound healing, cancer therapy), gene therapies,delivery of viral vectors (e.g., construct delivery methods).

EXAMPLES Example 1 Synthesis of Biodegradable Non-Gelling AmphilicPentablock Co-Polymer (PTSsol)

In this example, a pentablock co-polymer having a PEG-PCL-PLA-PCL-PEGblock configuration was prepared.

For synthesis, a polyethylene glycol-polycaprolactone (PEG-PCL) diblockcopolymer was synthesized by ring opening polymerization ofε-caprolactone with monomethoxy polyethylene glycol (m-PEG) using tinoctoate as a catalyst. First, mPEG 2000 and ε-caprolactone were added ina round bottom flask equipped with a stir bar. Polymer was vacuum purgedfour times with nitrogen, followed by addition of 0.5 wt % of m-PEG andε-caprolactone combined of tin octoate catalyst. The reaction mixturewas heated to 130° C. for 36 hours under nitrogen (Step 1). Next, theresulting diblock copolymer was re-heated to 130° C. and L-lactide wasadded. The reaction mixture was vacuum purged four times with nitrogenfollowed by addition of 0.5 wt % of entire DB and lactide combined oftin octoate catalyst and the reaction mixture was heated to 130° C. for36 hours under nitrogen (Step 2).

The resulting triblock polymer was then dissolved in dichloromethane andprecipitated by addition of chilled heptanes (cooled to −78° C.).Heptane is then decanted and the precipitate was vacuum-dried to removeany residual solvents.

Then, the resulting triblock copolymer was coupled utilizinghexamethylenediisocyanate (HMDD as a linker to preparePEG-PCL-PLA-PCL-PEG pentablock copolymers. Coupling reaction was carriedout at 80° C. for 8 hours (step 3). The resulting polymer is re-purifiedby precipitation and tin is scavenged. The purified amphiphilicpentablock co-polymer is stored at −20° C. Synthesis ofPEG-PCL-PLA-PCL-PEG block configuration is:

Example 2 Synthesis of Thermosensitive Biodegradable Gelling PentablockCo-Polymers (PTSgel)

PTSgel with PEG-PCL-PLA-PCL-PEG block arrangements were synthesized aspreviously described in U.S. Pat. No. 8,551,531, U.S. Publication No.20160090444, Patel et al. (Novel Thermosensitive Pentablock Copolymersfor Sustained Delivery of Proteins in the Treatment of PosteriorSegments Diseases, (2014) pp 1185-1200) and Patel et al. (Tailor-madepentablock copolymer based formulation for sustained ocular delivery ofprotein therapeutics, Invest. Ophthalmol. Vis. Sci. 55 (2014) p 4629),all of which are incorporated herein by reference in their entirety.Briefly, the diblock copolymer was synthesized by ring-openingcopolymerization of ε-caprolactone with monomethoxy PEG using tinoctoate as a catalyst. The resulting diblock copolymer was similarlyconverted to triblock by adding L-lactide. The resulting triblockcopolymer was coupled utilizing hexamethylenediisocyanate (HMDI) as alinker to prepare PEG-PCL-PLA-PCL-PEG pentablock copolymers. Thepurified pentablock co-polymer is stored at −20° C., until used.

Example 3 Synthesis of Non-Gelling PTSsol Polymers

Several biodegradable non-gelling PTSsol polymers were synthesized,including:

-   -   (i) (PTS-1-0GH) PEG₅₅₀-PCL₅₀₀-PLA₈₀₀-PCL₅₀₀-PEG₅₅₀ (MW=2900,        PEG=37.9%)    -   (ii) (PTS-120GH) PEG₁₀₀₀-PCL₅₀₀-PLA₁₀₀₀-PCL₅₀₀-PEG₁₀₀₀ (Mw=4000,        PEG=50.0%)    -   (iii) (PTS-121GH) PEG2000-PCL₅₀₀-PLA₁₀₀₀-PCL₅₀₀-PEG₂₀₀₀        (Mw=6000, PEG=66.6%)    -   (iv) (PTS-123GH) PEG₅₀₀₀-PCL₅₀₀-PLA₁₀₀₀-PCL₅₀₀-PEG₅₀₀₀        (Mw=12000, PEG=83.3%)    -   (v) (PTS-302GH)        PEG_(475(400+550 in 1:1 ratio))-PCL₅₀₀-PLA₂₅₀-PCL₅₀₀-PEG₄₇₅        (MW=2200, PEG=43 .2%)

The polymers used herein (e.g., gelling polymers: 101GH (MW: 3,000 Da),10GH (MW: 3,100 Da), 102GH (MW: 3,300 Da), 103GH (MW: 3,600 Da), 113GH(MW: 3,500 Da), 122GH (MW: 3,500 Da) and non-gelling polymers: 1-0GH(MW: 2900 Da), 120GH (MW: 4,000 Da), 121GH (MW: 6,000 Da), 123GH (MW:12,000 Da)) may be constructed with different block sizes of m-PEG, PCLand PLA with PLA in the center of the molecule(m-PEG-PCL-PLA-PCL-PEG-m). The molecular weight ranged between2200-12,000 Da, with a gradual increase in the hydrophobicity ofmolecules for gelation polymers, and an increase in hydrophilicity fornon-gelling polymers. For gelling polymers, the objective was to varymolecular weights and hydrophobic-hydrophilic block ratios in thepolymers to achieve modulation of drug release. For aqueous polymers,the objective was to vary molecular weights and hydrophobic-hydrophilicblock ratios in the polymers to achieve hydrophobic active agentsolubility while maintaining an aqueous composition that does notvisibly gel at body temperature but becomes slightly more viscous toextend contact time and hence provide higher drug penetration in thetissue/organ, it is applied to.

Without wishing to be bound by theory, it is believed that the liquidamphiphilic pentablock co-polymer formulation described herein, whenapplied topically to eye surprisingly becomes bioadhesive or viscous(possibly without blurring), significantly increases contact time (e.g.,1-48 hours and longer) with ocular surface and hence allows higher drugpenetration into the eye. Another advantage is that the liquidpentablock co-polymer formulation described herein can include smallparticles (<1 μm size is diameter, e.g., 10-200 nm), likely formingmicelles which also help improve drug penetration into the eye. Smallparticle size because of their size and nature can avoid elimination byphagocytosis and are able to penetrate a cellular layer much more easilyand hence increase in drug concentration. Indeed, as measured by DLS(see Example 12), particle size diameter can be <1 μm and preferably<200 nm and more preferably <100 nm and most preferably <30 nm. Whenapplied topically to the eye, PTSsol may be able to deliver drugs to theback of the eye in sufficient concentration to be of therapeutic value.

As such, both the bioadhesive property of the polymer which increasescontact time and the increased cellular penetration due to its smallparticle size composition make the formulations disclosed herein uniquein resulting higher concentrations in the target tissue/organ by simpletopical application. Conventional sustained release formulations areeither mucoadhesive or mucopenetrating, not both. The pentablock PTSsolformulations disclosed herein unexpectedly have both properties. Due tosmall particle size of amphiphilic nature, which would easily dispersein aqueous formulation without the help of organic solvents orsonication etc., evade elimination by immune system, high loadingcapacity of hydrophobic and/or hydrophilic drug, biocompatible andbiodegradable, mucoadhesive and muco-penetratable nature, this resultsin a very unique sustained drug release formulation including but notlimited to for topical, dermal, intravitreal or parenteral applications.

Example 4 Difficult to Formulate Hydrophobic Active Agent AqueousCompositions Using PTS 1-0 GH or PTS121 GH Polymer

In this example, the polymer PTS1-0 GH was used to formulate aqueouscompositions of difficult to suspend hydrophobic active agents.Hydrophobic active agents that are difficult to formulate in aqueouscompositions are typically formulated as emulsions or suspensions. UsingPTS polymer solutions (PTSsol), these difficult to formulate hydrophobicdrugs can form aqueous compositions at significantly high drugconcentrations, as clear liquids in hydrophilic PTSsol dispersions, togenerate a useful topical formulation. For example, a 10% PTS1-0GHPTSsol was used to dissolve up to 1% cyclosporine and up to 2.5%brinzolamide, resulting in clear liquids. The PTSsol formed a stableformulation, stored at room temperature or refrigerated at 4° C.,remained clear up to 8 weeks of testing. Higher concentrations forcyclosporine or brinzolamide are feasible. Similarly, PTSsol for 0.5%celecoxib was prepared in 10% PTS121GH in PBS buffer at pH 7.4.Referring to FIG. 1, left panel, a formulation of 1% cyclosporine and upto 2.5% brinzolamide were prepared in clear aqueous solutions, whichremained stable over 8 weeks. Referring to FIGS. 2 and 3 the stabilityof 2.5% brinzolamide in 25% 1-0 GH polymer dispersion in PBS at pH 7.4was analyzed over 8 weeks, using HPLC.

Example 5 Difficult to Formulate Hydrophobic Active Agent AqueousCompositions Using PTS113GH or PTS122GH and PTS 121GH Polymers

In this example, the polymer PTS113 GH and PTS122 GH was used toformulate aqueous compositions of especially difficult to suspendhydrophobic active agents. Especially hydrophobic active agents aredifficult to formulate in aqueous compositions and may not directlydissolve in hydrophilic polymers (PTSsol), such as 121 GH. For example,difluprednate, a difficult to suspend active agent, does not readilydissolve in PTS121 GH polymer. However, difluprednate can first bedissolved in very small amounts of relatively hydrophobic gellingpolymer, such as 113 GH or 122 GH to form a solution/dispersion, whichis then subsequently mixed with PTS121 GH to maintain the aqueousformulations at body temperature. Using this method, stable aqueousformulations of up to a 0.1% difluprednate were achieved. Referring toFIG. 1, right panel, a formulation of 0.07% and 0.1% difluprednate wereprepared as clear aqueous solutions.

Example 6 Formulation of Aqueous Compositions Containing Hydrophilic andHydrophobic Active Agents

In this example, aqueous compositions containing hydrophilic andhydrophobic active agents are formulated using PTSsol polymers. First, ahydrophobic active agent is dissolved into PTSgel (e.g., PTS 113 GH orPTS122 GH polymers as described in Example 5) followed by addition ofhydrophilic non-gelling polymer, PTS121GH to form a PTSsol aqueousformulation. Second, the hydrophilic active agent such as IgG is thenmixed into the PTSsol aqueous formulation containing the hydrophobicactive agent. The resulting aqueous composition contains a stableformulation of hydrophilic and hydrophobic active agents.

Example 7 Artificial Tear Composition Using PTS121 GH Polymers

In this example, an artificial tear composition using PTSsol polymerswas generated. PTS solutions are clear, bioadhesive, biocompatible, andbiodegradable polymers ideal for sensitive medical applications, such aspreparing artificial tears for relieving eye discomfort caused by dryeye. Due to increase in viscosity of PTSsol at body temperature, thepolymer remains at the surface of which they are applied to for anextended period of time. For example, 5-20% PTS 121GH polymers wereprepared in PBS at pH 7.4 as vehicle PTSsol, with no active agent. Theformulations remained clear for 21 days stored at room temperature aswell as at 4° C. The 121GH PTSsol polymer aqueous dispersions are readyto be tested in healthy animals and in disease models. Referring to FIG.4, formulations of artificial tears consisting of 5, 10, 15, and 20%121GH polymer were prepared as clear aqueous solutions, which remainedvisibly clear over 21 days. Additional excipients can be added to theformulation as desired.

It should be noted that artificial tear preparation can be used as alubricant for joints or wound cover or adhesive and other similarapplications.

Example 8 PTSsol Remains Liquid

FIGS. 5A-5B show that exemplary PTSsol are liquid at both 4° C. and atbody temperature (about 37° C.).

Example 9 Inhibition of Polymer Gelation

In this example, PTSsol polymers were used to inhibit the gelation ofgelling polymers (PTSgel). For example, PTSsol polymers do not gelinstantly at body temperature, but also when added, in some amounts toan aqueous solution of the gelling pentablock co-polymers, preventgelling of the polymers which otherwise inherently would gel instantly.A volume of 250 uL of PTS121GH polymer was added to 4 mL of 25% PTS103GHor PTS113GH solution. As a result of the addition of 250 uL of 121GH,neither the PTS103 GH nor PTS113 GH solution achieved instant gelationat 37° C. The inhibition of polymer gelation is extremely useful forsolubilizing certain drugs that would need a gelling hydrophobic polymerto dissolve but when mixed with non-gelling hydrophilic polymer willremain liquid at body temperature (about 37° C.) for significantly longperiods (such as about 4 hours or longer).

Example 10 NMR Analysis of PTS 121GH

¹H-NMR Analysis. Purity, molecular structure and molecular weight (Mn)of the PTSsol were analyzed utilizing a Mercury 300-MHz NMRspectrometer. ¹H-NMR spectrograms were recorded by dissolving thepolymers in deuterated chloroform (CDCl₃).

A Mercury 300-MHz NMR spectrometer was employed to characterize thepentablock co-polymers. FIG. 6 depicts ¹H-NMR spectra of PTS121GH indeuterated chloroform. As described in FIG. 6, typical ¹H-NMRcharacteristic peaks were observed at 1.55, 2.30 and 4.04 δ ppmrepresenting methylene protons of —(CH₂)₃—, —OCOCH₂—, and —CH₂OOC— ofPCL units, respectively. A sharp peak at 3.64 δ ppm was attributed tomethylene protons (—CH₂CH₂O—) of PEG. Typical signals at 1.50 (—CH₃) and5.17 (—CH—) δ ppm were assigned for PLA blocks. Whereas, a peak at 3.36δ ppm was denoted to terminal methyl of (—OCH3—) of PEG. The[EO-[CL]-[LA] molar ratios of final products were calculated fromintegrations of PEG signal at 3.36 δ ppm, PCL signal at 4.04 δ ppm andPLA signal at 5.17 δ ppm. PEG signal at 3.36 δ ppm was applied for thecalculation of molar ratio of various blocks within the pentablockco-polymer. Estimated molecular weight, calculated using NMR, was closeto theoretical feed ratio.

Example 11 GPC Analysis of PTS 121GH

Molecular weights (Mn and Mw) and polydispersity of polymers wereexamined by Gel Permeation Chromatography (GPC) analysis. Briefly, 20 mgof polymer was dissolved in 1 mL of tetrahydrofuran (THF). Polymersamples were separated on two oligopore columns (Agilent, Santa Clara,Calif.) connected in series and maintained at 40° C. Solvent THF at therate of 0.5 mL/min was utilized as eluting solvent. Samples wereanalyzed on Wyatt technologies MINI DAWN instrument (S. No. 528-T)connected to OPTILAB DSP interferometric refractometer, using ASTRA 6software.

Molecular weight (Mw and Mn) and polydispersity of polymers weredetermined by GPC. A typical GPC chromatogram of 121GH pentablockco-polymer is shown in FIG. 7. A single peak for the polymer wasobserved suggesting unimodal distribution of molecular weight andabsence of any other homopolymer block such as PEG, PCL or PLA.Polydispersity (PDI) for the co-polymers was 1.053 indicating narrowdistribution of molecular weights.

Example 12 DLS Analysis of PTS 1-0 GH

Preparation and Size Characterization of Pentablock Copolymers UsingDynamic Light Scattering (DLS): An amphiphilic pentablock co-polymer(1-0GH) was dissolved at 1 mg/mL in HPLC pure water and stored at 4° C.until analyzed. The solution was analyzed for particle size by DLS witha Wyatt 233-MOB Mobius instrument (Mw-R model: Globular proteins). Theanalysis was performed at an angle of 163.5° at 20° C. The mean radiiwere obtained after five runs of ten acquisitions. The results are shownin FIG. 8. The particle size diameter measured by DLS for PTS 1-0GH was14.4 nm in diameter (7.2 nm radius).

Example 13 Brinzolamide Formulation (2.5%) in PTSsol and 8-WeekStability

PTSsol polymer dispersion provided a stable vehicle that resulted in aclear aqueous solution of a relatively high concentration (2.5%) of acommonly used, poorly soluble drug, brinzolamide (BRZ) in PTSsol1-0GH-L2 (25% in PBS, pH 7.4). This formulation was tested for loweringpotential of IOP and tolerability in normotensive dogs. Formulated BRZwas analyzed using an HPLC method described below.

HPLC Method Chromatographic Conditions

-   Column: Phenomenex Kinetex C18, 5 μm, 100 Å (250 mm×4.6 mm)-   Mobile phase:

Time (min) A (%) B (%) 0 90 10 5 90 10 10 50 50 15 50 50 20 10 90 25 1090 27 90 10 30 90 10

-   Buffer A: 0.01M Ammonium acetate buffer pH 3.8-   Preparation: Weigh 0.7708 g of Ammonium acetate and dissolve it in 1    L HPLC water. Adjust the pH to 3.8 using acetic acid.-   Buffer B: HPLC grade methanol-   Flow rate: 1000 μL/min-   Column temperature: 25° C.-   Wavelength: 254 nm-   Injection volume: 10 μL

HPLC analysis of formulated drug showed that Brinzolamide was stable at4° C. for the tested period of up to 8 weeks. Specifically, FIG. 2 showsBrinzolamide (2.5%) in PTSsol (PTS 1-0GH, 25% in PBS, pH 7.4), after 8weeks of storage at 4° C. (peak with RT 12.954 is Brinzolamide).

Example 14 Stability Testing of Brinzolamide Formulation at 4° C. and atRoom Temperature (about 20° C.)

In a parallel experiment, stability of formulated Brinzolamide (1%) inPTSsol (PTS 1-0 GH, 25% in PBS, pH 7.4) was tested for stability, storedrefrigerated (about 4° C.) or under ambient conditions (about 20° C.).

FIG. 3 shows stability of Brinzolamide (1%) formulated in PTSsol (PTS1-OGH, 25% in PBS, pH 7.4), after 8 weeks of storage in the refrigerator(about 4° C.) or under ambient conditions (about 20° C.).

Example 15 Ocular Surface Retention of NIR-IgG (Formulated in PTSsol) inMice

All animal protocols were conducted according to the ARVO Statement forthe Use of Animals in Ophthalmic and Vision Research.

A PTSsol polymer 1-0GH-L2 (MW 3100 DA) was synthesized, which remainedin liquid phase at room temperature and at 37° C. Corneal retention timewas evaluated by applying PTSsol containing NIR-labeled IgG (IRDye800CW,LICOR Biosciences, Lincoln, Nebr.) to the corneal surface of mice andmonitored by in vivo imaging (IVIS, Xenogen, Alameda, Calif.).

IgG was labeled with a near-infrared (NIR) dye (IRDye 800CW by LICORBiosciences, Lincoln, Nebr.). NIR-IgG in a buffer (PBS-phosphatebuffered saline, pH 7.4) or in PTSsol solution (25% polymer dispersionin PBS, pH 7.4%) was made by adding 200 uL of PTSsol dispersion or PBSto 0.2 mg of lyophilized NIR-labeled IgG, resulting in an 0.8 mg/mL(0.08%) final NIR-IgG concentration. After gentle vortexing, thesolutions were stored at 4° C. until being used within 24 hours.

Mice (n=3/group) were dosed with PTSsol solution or PBS solution withboth containing NIR-IgG. A volume of 2 uL of the NIR-IgG solution wasapplied to the right cornea of anesthetized mice (1-3% isoflurane in O₂)for serial in vivo imaging (IVIS, Xenogen, Alameda, Calif.) usingIndocyanine Green (ICG) settings. NIR-IgG fluorescence was quantifiedusing the IVIS imaging software automatic region of interest (ROI)setting to calculate the radiant efficiency of the NIR-IgG signal on thecorneal surface of each eye. Mice were maintained under generalanesthesia for the first 15 minutes of imaging, then allowed to recoverbetween each subsequent imaging session. Images were obtainedpre-application (time 0), then 1, 5, 10, 15, 30, 60, 90, and 120 minutespost-application, and every hour up to 12 hours, if fluorescence signalwas still present. If signal was still present at the 12-hour timepoint, additional imaging was performed the following morning at 21hours post-application.

NIR-IgG in PBS was barely detected 2 hours post application on theocular surface of mice, whereas NIR-IgG in PTSsol using 1-0GH polymerremained on the ocular surface for >21 hours (FIG. 9). Also, the PTSsolformulation was well tolerated, without signs of inflammation at anytime point.

Specifically, FIG. 9 shows in vivo imaging of NIR-IgG in PBS or PTSsolafter topical ocular application in the right eye in mice. Retention ofNIR-IgG on ocular surface: less than 2 h in PBS (Top row); greater than7 hours in PTSsol 121GH (Middle row) and greater than 21 hours in PTSsol10-GH-L2 (bottom row). Graph: Region of interest (ROI) concentrationintensity calculated by imager (N=3 mice per group).

The experiment clearly demonstrates using a labeled IgG protein in thePTSsol, that the IgG was retained on the ocular surface or corneafor >21 hours. This suggests that once a day topical application ofdrugs (Biologics or chemical) for anterior segment of the eye isfeasible.

Example 16 Dosing of Brinzolamide in PTSsol, Tolerability, IOPMonitoring in Normotensive Dogs

All animal protocols were conducted according to the ARVO Statement forthe Use of Animals in Ophthalmic and Vision Research. Six normotensivemixed-breed dogs were dosed 3 consecutive days with PTSsol vehicle qd,Brinzolamide (BRZ) 2.5% in PTSsol (25% PTS 1-0 GH-L2 in PBS buffer, pH7.4) qd, and commercial BRZ 1% (Azopt) tid. IOP was measured at 7 am and3 pm for each treatment day and at 7 am for two days followingtreatment. Ocular exams were performed daily to monitor tolerability.

All IOP measurements were obtained by rebound tonometry (TonoVet®,icare, Helsinki, Finland) with a disposable probe held horizontally, 4-5mm from the corneal surface. Three independent IOP readings wereobtained from each eye, and the mean of the three averaged readings wasused at the IOP for each time point. The same instrument as usedthroughout the acclimation and experiment periods. Each dog was gentlyrestrained for readings without use of sedatives. Baseline IOP wasmeasured in six normotensive, for three consecutive days. The left eye(OS) in all dogs, in all periods served as the treated eye and the righteye (OD) served as the untreated control eye. Dogs were dosed with 50 uLof an individual solution to the corneal surface for three consecutivedays, with four untreated days between treatments.

As evident from the data presented in the Table below and FIG. 10, byday 3 of dosing, IOP was significantly lower in Azopt tid and 2.5% BRZin PTSsol qd dosed eyes compared to vehicle or baseline at both 7 AM and3 PM (P<0.014). On day 5, 48 hours after dosing, IOP remainedsignificantly lower in eyes dosed previously with 2.5% BRZ PTSsol qdcompared to those dosed with Azopt tid (P=0.036).

TABLE Mean +/− SEM difference in intraocular pressure (IOP) between OS(dosed) and OD (not dosed) Day and time of IOP measurement Day 1 Day 1Day 2 Day 2 Day 3 Day 3 Day 4 Day 5 Group 7 AM* 3 PM 7 AM* 3 PM 7 AM* 3PM 7 AM** 7 AM** Baseline −0.34 ± 0.6 −0.93 ± 0.3 0.38 ± 0.6 −0.13 ± 0.4−0.67 ± 1.0  −0.2 ± 0.7  — — PTSsol −0.93 ± 0.3 −0.13 ± 0.4 −0.2 ± 0.7−0.73 ± 0.4  0.2 ± 0.4 −0.47 ± 0.3   −0.27 ± 0.6  −0.13 ± 0.4  vehicle(qd) Azopt (tid) −0.33 ± 0.7  −2.2 ± 0.6^(a) −2.0 ± 1.0   −2.6 ± 0.4^(b)−2.3 ± 0.5^(c) −1.6 ± 0.7^(d) −1.4 ± 0.5 0.47 ± 0.5 2.5% BRZ in  1.1 ±0.4  −3.4 ± 1.2^(a) −1.3 ± 0.9  −1.3 ± 2.2 −3.1 ± 0.3  −2.4 ± 0.4^(d)−2.1 ± 0.2  −1.3 ± 0.4^(f) PTSsol (qd) *prior to first treatment of theday; **no treatments on days 4 and 5 BRZ—brinzolamide; qd—dosed once aday (following IOPs at 7 AM), tid—dosed every 8 hours

FIG. 10 shows IOP measurement in normotensive mixed breed dogs (n=6).

Ocular examinations using a slit-lamp biomicroscope (S1-17, KOWA, Tokyo,Japan) and modified Hackett-McDonald ocular irritation scoring wereperformed 30 minutes after the AM dose each day and for 2 days (in theAM) following dosing to monitor tolerability.

Topical ocular application of PTSsol vehicle qd, and PTSsol 2.5% BRZ qdwere well tolerated by the dogs during 3 days of dosing and for the 2days following dosing. On slit-lamp examination, there were no signs ofconjunctival hyperemia, chemosis, or other signs of ocular inflammationin any of the dosing groups on any day.

Sustained lowering of 48 hours (and potentially longer but not yettested) post-dosing suggests that a PTSsol of 2.5% BRZ, which was welltolerated, may allow once a day, or less frequent, dosing, for treatmentof glaucoma.

A formulation containing PTSsol may be useful for sustained topicalocular drug delivery of antibiotics, antifungals, other anti-glaucomadrugs, and anti-inflammatories and other drugs as needed. Furthermore,depending on the ocular pharmacokinetics of the individual drugs, PTSsolmay enhance drug delivery to the ocular posterior segment for treatmentof age related macular degeneration or diabetic retinopathy, asexamples.

Various aspects of the present disclosure may be used alone, incombination, or in a variety of arrangements not specifically discussedin the embodiments described in the foregoing and is therefore notlimited in its application to the details and arrangement of componentsset forth in the foregoing description or illustrated in the drawings.For example, aspects described in one embodiment may be combined in anymanner with aspects described in other embodiments.

Use of ordinal terms such as “first,” “second,” “third,” etc., in theclaims to modify a claim element does not by itself connote anypriority, precedence, or order of one claim element over another or thetemporal order in which acts of a method are performed, but are usedmerely as labels to distinguish one claim element having a certain namefrom another element having a same name (but for the use of the ordinalterm) to distinguish the claim elements.

Also, the phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. The use of“including,” “comprising,” or “having,” “containing,” “involving,” andvariations thereof herein, is meant to encompass the items listedthereafter and equivalents thereof as well as additional items.“Consisting essentially of” means inclusion of the items listedthereafter and which is open to unlisted items that do not materiallyaffect the basic and novel properties of the disclosure.

INCORPORATION BY REFERENCE

All publications and patents mentioned herein are hereby incorporated byreference in their entireties as if each individual publication orpatent was specifically and individually indicated to be incorporated byreference.

1. A composition for delivery of an active ingredient, comprising ablock polymer having the formula of PEG-PCL-PLA-PCL-PEG orPGA-PCL-PEG-PCL-PGA or PLA-PCL-PEG-PCL-PLA or PCL-PLA-PEG-PLA-PCL orPCL-PGA-PEG-PGA-PCL in the form of an aqueous dispersion, wherein PEG ispolyethylene glycol and has an average molecular weight of about 100 toabout 10,000 Da and a molecular weight percentage of at least 25%,wherein preferably PEG has an average molecular weight of about 500 toabout 5,000 Da; wherein PCL is poly(ε-caprolactone) and has an averagemolecular weight of about 100 to about 3000 Da, preferably about 200 toabout 2000 Da, and more preferably about 300 to about 1500 Da; whereinPLA is polylactic acid having an average molecular weight of about 100to about 5,000 Da, preferably about 150 to about 3000 Da, and morepreferably about 200 to about 1500 Da; wherein PGA is polyglycolic acidhaving an average molecular weight of about 100 to about 5,000 Da,preferably about 150 to about 3000 Da, and more preferably about 200 toabout 1500 Da; and wherein the polymer preferably has a total molecularweight of about 1,500 to about 20,000 Da, more preferably about 2,000 toabout 15,000 Da, even more preferably about 2500 to about 10,000 Da. 2.The composition according to claim 1, wherein the polymer does notvisibly gel at about body temperature instantly.
 3. The compositionaccording to claim 1, wherein the polymer is a non-gelling polymer andthe composition further comprises a gelling polymer wherein thenon-gelling polymer prevents instant gelation of the gelling polymer. 4.The composition according to claim 3, wherein the gelling polymer ispresent at about 0.01 to about 25 wt % of liquid formulation, preferablyabout 1 to about 15 wt %, more preferably about 2 to about 10 wt %. 5.The composition according to claim 4, further comprising an activeingredient that is hydrophobic and is dissolved in the gelling polymer.6. The composition according to claim 1, wherein the non-gelling polymeris present at between about 0.01 wt % and about 50 wt % of liquidformulation, preferably about 1 to about 35 wt %, more preferably about2 to about 25 wt %.
 7. The composition according to claim 6, furthercomprising an aqueous medium and an active ingredient admixed therein.8. The composition according to claim 7, wherein the aqueous medium iswater or aqueous buffer.
 9. The composition according to claim 7,wherein the active ingredient is present at about 0.01 wt % to about 50wt % of liquid formulation, preferably about 0.1 to about 30 wt %, morepreferably about 0.2 to about 10 wt %.
 10. The composition according toclaim 7, wherein the active ingredient is a biologic or chemical agent.11. The composition according to claim 7, wherein the active ingredientis hydrophobic or hydrophilic, or a mixture of hydrophobic andhydrophilic ingredients.
 12. A method for preparing an aqueousformulation of a hydrophobic active ingredient, comprising: dissolvingthe hydrophobic active ingredient in a gelling polymer, and admixingwith the composition of claim 1, wherein the non-gelling polymer ispresent at about 0.01 to about 49.9 wt % of liquid formulation,preferably about 1 to about 35 wt %, more preferably about 2 to about 25wt %.
 13. An artificial tear or lubricant for joint or wound cover oradhesive comprising an aqueous solution of the composition of claim 1.14. The artificial tear of claim 13 wherein the aqueous solutionincludes one or more of hydrophilic polymer excipients, tonicity agents,buffers, sugars selected from trehalose, mannose, D-galactose, andlactose, preservatives, co-solvents or antioxidants etc.
 15. Theartificial tear of claim 14 wherein the aqueous solution has a pHranging from about 5.0 to about 8.0, preferably about 6.6 to about 7.4,and more preferably about 7.0.
 16. A method of delivering an activeingredient to a mammal in need thereof, comprising: providing thecomposition of claim 1 admixed with an active ingredient, wherein thepolymer is present at between about 0.01 wt % and about 50 wt % ofliquid formulation, preferably about 1 to about 35 wt %, more preferablyabout 2 to about 25 wt %; wherein the composition is in the form of areasonably clear polymer dispersion; and administering the compositionto a mammal; wherein preferably the method provides sustained release ofthe active ingredient.
 17. The method of claim 16, wherein saidadministering is by a topical (e.g., ocular or dermal surface), oral orparenteral route.
 18. The method of claim 16 wherein the polymer clearsat a release rate substantially similar to an active ingredient,allowing for repeat applications without interfering biologically orphysically with a prior application.
 19. The method of claim 16, whereinthe polymer biodegrades successively into substituent blocks, which arenot substantially physiologically harmful, and wherein the polymer andthe substituent blocks from biodegradation are tolerated in vivo suchthat long-term or repeat applications are feasible.
 20. The method ofclaim 16, wherein the composition is administered to an ocular surfaceand provides relief or sustained release of the active ingredient for1-48 hours or longer.
 21. (canceled)